Conversion of hydrocarbon oils



Oct. 19, 1937. c. H. ANGELL 2,095,952

CONVERSION OF HYDROCARBON OILS Filed Feb. 27, 1955 FURNACE TOPPINGCOLUMN INVENTOR CHARLES; H. ANGELL Patented Oct. 19, 1937 UNITED STATESCONVERSION OF HYDROCARBON OILS Charles H. Angell, Chicago, Ill.,assignor to Universal Oil Products Company, Chicago, 111., a corporationof'Delaware Application February 27, 1933, Serial No. 658,707

2 Claims.

' 15 tions obtained therein which are selected as most desirable for thefurther treatment of said intermediate conversion products.

It is within the scope of the present invention either to subject thetotal reflux condensate 20 formed by fractionation of the vaporousconversion products of the process to the same treatment as thatafforded the high boiling components of the charging stock or toseparate the reflux condensate and, when desired, the topped 25 chargingstock, into low boiling and high boiling fractions, returning said lowboiling fractions to conversion together with the low boiling fractionsof the charging stock separated therefrom by the topping operation andsubjecting said 30 high boiling fractions to independently controlledless severe conversion conditions in a separate heating coil. Thefeatures and advantages of the present invention will be apparent tothose familiar with the prior art from the foregoing brief 35description of the process and from the following more detaileddescription of the accompanying diagrammatic drawing. The drawingillustrates one specific form of apparatus embodying the features of thepresent invention and in which 40 the process of the invention may bepracticed.

Referring to the drawing, raw oil charging stock for the process, whichmay comprise, for example, crude petroleum or other hydrocarbon oilcontaining a substantial proportion of motor 45 fuel or motor fuelfractions as well as higher boiling components and including, whendesired, such materials as pressure distillate containing motor fuelresulting from cracking but of poor antiknock value, is supplied inheated state 50 through line I and valve 2 to topping column 3,

comprising, in the case illustrated, a fractionator of any suitable formwhereby the gasoline components of the changing stock, which enter thecolumn in vaporous form, are separated from 55 its higher boilingcomponents, which either enter the column as liquid or' are condensed byfractional condensation in this zone, It will be understood that the rawoil is introduced into column 3 at a temperature somewhat in excess ofthe end-boiling point of the light product which it is desired toseparate from the higher boiling fractions of the charging stock,although specific means for accomplishing heating and total or partialvaporization of the charging stock are not shown. The temperature towhich the oil is heated, prior to its introduction into column 3 mayrange, for example, from 400 to 600 F., or more, and the pressureemployed in column 3 may range from substantially atmospheric or aslight subatmospheric pressure to a superatmospheric pressure of 100pounds per sq. in., substantially atmospheric pressure being preferred.Heating of the oil may be accomplished in a suitable heating coildisposed in any well known form of furnace (not shown), which will beindependently fired or supplied with flue gases from the crackingfurnace of the process, or the required heat may be recovered byindirectly contacting the charging stock with any suitable hot vaporousor liquid products of the process by means of suitable heat exchangersof any well. known form, not shown in the drawing, or any combination ofthe methods mentioned may be utilized for heating the charging stock tothe temperature required for the topping operation.

Low-boiling fractions of the charging stock, of the desired end-boilingpoint, separated from its higher boiling components in column 3 are withdrawn in vaporous form, together with any gas resulting from the toppingoperation, from the upper portion of the topping column through line 4and valve 5 to be subjected to condensation in condenser 6, from whichthe resulting distillate and gas passes through line I and valve 8 tocollection and separation in receiver 9.

While the distillate thus collected in receiver 9 preferably containsall of the gasoline components of the charging stock boiling up to 400F., 7

which may be regulated to suit requirements by any well known method,not shown, of controlling the vapor outlet temperature from the upperportion of column 3. It is also within the scope of the invention,although not shown in the drawing, when the charging stock containscertain predetermined motor fuel fractions of sufiiciently goodantiknock value to warrant no reforming treatment, to separately recoversuch selected fractions from topping column 3 by well known means, notshown, subjecting the remaining portion of the motor fuel of inferiorantiknock value to reforming, as will be presently more fully described,while the selected fractions of good antiknock value are preferablyblended with the final motor fuel products of the process.

Uncondensable gas is released from receiver 9 through line l and valve Aportion of the distillate collected in receiver 9 may, when desired, bewithdrawn to storage or to any desired further treatment through line l2and valve l3. However, at least a portion of the distillate collected inreceiver 9 is withdrawn therefrom through line 4 and valve |5 to pump |6by means of which it is fed through line l1 and valve l8 to heating coilI9 for further treatment.

Heating coil I9 is located Within a furnace 20 of any suitable form bymeans of which heat is supplied to the oil passing through the heatingcoil to bring it to the desired temperature, preferably at a substantialsuperatmospheric pressure, the conditions in heating coil l9 beingregulated to effect a markedirnprovement in the motor fuelcharacteristics of the oil supplied to this zone,

particularly with respect to its antiknock value, without excessivelyaltering its boiling range. The heated oil may be discharged fromheating coil I9 through line 2| and valve 22 into reaction chamber 23.

Chamber 23 is also preferably maintained at a substantialsuperatmospheric pressure and, although not shown in the drawing, thiszone is preferably well insulated to prevent excessive loss of heat byradiation so that conversion of the oils introduced into the reactionchamber, and particularly their vaporous components. may continuetherein. Both vaporous and liquid conversion products are withdrawn fromthe lower portion of chamber 23 and are introduced through line 24 andvalve 25 into vaporizing chamber 26.

Chamber 26 is preferably maintained at a substantially reduced pressurerelative to that employed in chamber 23, by means of which furthervaporization of the liquid conversion products is accomplished and thevapors are separated from the final residual products of the process.The residual liquid remaining unvaporized in chamber 26, when desired asthe final residual product of the process, is withdrawn therefromthrough line 21 and valve 28 to cooling and storage or to any desiredfurther treatment. Means will be later more fully described for securingthe production of coke in chamber 26 as the final residual product ofthe process. The vaporous products of the process pass from chamber 26through line 25 and valve 30 to fractionation in fractionator 3|.

Simultaneous with the operation above described the high-boilingcomponents of the charging stock, withdrawn as bottoms from the toppingand fractionating operation in column 3 through line 32 and valve 33 topump 34, are supplied therefrom through line 35 and valve 36 tofractionator 3|, to commingle therein with the hot vaporous conversionproducts of the process Sup,

plied to this zone from chamber 26, as described, being therebysubjected to vaporization and the same fractionation as that affordedthe vaporous conversion products of the process in this zone and, at thesame time, assisting fractionation of the vapors. When desired, aportion or all of the topped charging stock, instead of passing tofractionator 3| may be diverted from line 35 through line 52 and valve53 into line 50, passing therewith together with the total refluxcondensate or with the high-boiling components of the reflux condensatefrom fractionator 3|, as will be later more fully described, toconversion in heating coil 54.

Fractionated vapors of the desired end-boiling point, preferablycomprising materials within the boiling range of motor fuel and of goodantiknock value, are withdrawn, together with uncondensable gas producedby the cracking operation, from the upper portion of fractionator 3|through line 31 and valve 38 and are subjected to condensation andcooling in condenser 39, from which the resulting distillate and gaspasses through line 40 and valve 4| to collection and separation inreceiver 42. Uncondensable gas may be released from receiver 42 throughline 43 and valve 44. The distillate collected in receiver 42,comprising the final motor fuel conversion product of the process, maybe withdrawn through line 45 and valve 46 to storage or to any desiredfurther treatment. A portion of the distillate collected in receiver 42may, when desired, be returned, by well known means not shown in thedrawing, to the upper portion of fractionator 3|,

to assist fractionation of the vapors in this zone and to maintain thedesired vapor outlet temperature, thus controlling the end-boiling pointof the final light distillate conversion product of the process.

The vaporous products of the process, together with any topped chargingstock supplied to fractionator 3|, as described, are subjected tofractionation in this zone whereby their components boiling above theend-boiling point of the desired overhead vaporous product are condensedor remain unvaporized in this zone, collecting therein as refluxcondensate. All or, when desired, as will be later more fully described,only high-boiling components of the reflux condensate collect within thelower portion of fractionator 3| from which they are withdrawn throughline 41 and valve 48 to pump 49, by. means of which this oil is suppliedthrough line 50 and valve 5| to heating coil 54 commingling in line 50,as already described, with the topped charging stock or that portion, ifany, of this material supplied through line 52, valve 53 and line 50 toheating coil 54.

The oil supplied to heating coil 54 is subjected therein, by means ofheat supplied from a furnace 55 of any suitable form, to the describedconversion temperature, which is preferably somewhat lower than thatemployed in heating coil l9, and preferably at substantialsuperatmospheric pressure. The heated oil is discharged from heatingcoil 54 through line 56 and valve 51 into reaction chamber 23. It willbe understood that the heated oils from heating coils l9 and 54 may becommingled, as shown in the drawing, prior to their introduction intochamber 23, or that the two streams may be separately introduced intothe reaction chamber entering this zone at any desired point therein, bywell known is particularly desirable when the nature of the chargingstock and the other operating conditions of the process are such that asubstantial proportion of the reflux condensate formed in fractionator3| comprises relatively low-boiling oils which may be advantageouslysubjected to the same treatment in heating coil l9 as that afforded thedistillate from receiver 9, such lowboiling fractions of the refluxcondensate, including any fractions of the topped charging stocksupplied to the fractionator of similar boiling range and crackingcharacteristics, may be withdrawn as a side-stream from one or anynumber of suitable points in fractionator 3|, for example, through line58 and valve 59 to pump 60 by means of which these selected low-boilingfractions are fed through line GI and valve 52 into line H, comminglingtherein with the distillate from receiver 9 and passing therewith tofurther conversion in heating coil l9. 1

As another optional feature of the invention which is especiallyadvantageous when it is desirable to produce a heavy asphaltic or pitchyresidue or to entirely eliminate the production of liquid residue,producing only substantially dry coke as the residual product of the.process, all or any desired portion of the highly heated oil from heatingcoil l9 may be diverted from line 2| through line 63 and valve 64 intochamber 26, entering this zone at any desired point by preferably belowthe level of residual material therein; whereby additional heat isimparted to the residual oil suiiicient to reduce it to coke or to thedesired intermediate asphaltic or pitchy stage. When the process isoperated for the production of coke or semi-solid residue in chamber 26a plu rality of such zones may be employed, when de sired, although onlya single chamber is shown in the drawing. When a plurality of cokingchambers are utilized they may be operated simultaneously or,preferably, are alternately operated, cleaned and prepared for furtheroperation so that the duration of the operating cycle will not belimited by the capacity of the coking zone.

As already stated, the temperature of the charging stock entering thetopping column may range, for example, from 400 to 600 F., or more, andsubstantially atmospheric pressure is preferably employed in the toppingportion of the system, although subatmospheric pressure orsuperatmospheric pressures up to pounds, or more, per sq. in., may beemployed, when desired. A conversion temperature ranging, for example,from 950 to 1050 F. and a superatmospheric pressure of from 200 to 800pounds, or more, per sq. in. is preferably employed at the outlet fromthe heating coil to which the low-boiling fractions of the chargingstock from the topping operation are supplied. The other heatingcoil ofthe system to which are or high-boiling fractions of the refluxcondensate and topped charging stock are supplied preferably employs anoutlet temperature ranging, for example, from 875 to 975 F., with asuperatmospheric pressure measured at the outlet from the heating coilof from 100 to -500 pounds, or thereabouts, per square inch. Asuper-atmospheric pressure within the range of 100 tov 500 pounds, orthereabouts, may

be maintained in the reaction chamber. A substantially reduced pressureranging, for example, from 100 pounds or thereabouts per square inchdown to substantially atmospheric pressure is preferred in thevaporizing or coking chamber and this pressure may be eithersubstantially equalized or somewhat reduced in the succeedingfractionating, condensing and collecting portions of the crackingsystem.

As a specific example of one of the many possible operations of theprocess of the present invention, the charging stock is a 32 A. P. I.gravity crude containing approximately 27 percent. of 40.0" F. end pointgasoline of low antiknock value, fractions of the charging stock boilingup to approximately 500 F., are recovered by the topping operation andthe topped crude is subjected, together with reflux condensate from thefractionator of the cracking system to a conversion temperature ofapproximately 940 F., at a superatmospheric pressure of about 350 poundsper square inch at the outlet from the heating coil to which thismaterial is supplied. A pressure of about 350 pounds per sq. in. ismaintained in the reaction chamber. A reduced pressure of approximately60 pounds per sq. in. is maintained in the vaporizing chamber and issubstantially equalized in the succeeding portions of the crackingsystem. The distillate from the topping operation is subjected in aseparate heating coil to a conversion temperature of approximately 970F. at a superatmospheric pressure of about 600 pounds per sq. in. andthe heated oils from the two heating coils are commingled, prior totheir introduction into the reaction chamber. This operation may yield,per barrel of charging stock, about 76 percent of 400 end-point motorfuel having an antiknock value equivalent to an octane number ofapproximately 76, the additional products of the operation being about14 percent of good quality residual oil and about 460 cubic feet ofuncondensable gas.

In a somewhat different type of operation similar to that abovedescribed except that the temperature in the first mentioned heatingcoil is increased to about 950 F. and the highly heated oil from thereforming coil is introduced into direct contact with the residualmaterial in the reduced pressure chamber, coke is produced in this zoneas the residual product of the process and the yields from thisoperation are approximately as follows: 78 percent of 400 end-pointmotor fuel having an antiknock value equivalent to an octane number ofapproximately 75, about 47 pounds of coke and about 550 cubic feet ofuncondensable gas, per barrel, of charging stock.

In either of the operations above described by withdrawing a selectinglow-boiling fraction of the reflux condensate from the fractionator ofthe cracking system, having an end-boiling point approximatelycorresponding to or somewhat higher than that of the distillate from thetopping operation, and returning this material to reforming with saiddistillate, the antiknock value of the motor fuel produced may besomewhat increased at the expense of a somewhat lower yield of motorfuel and a slightly increased yield of gas.

I claim as my invention:

1. A conversion process which comprises fractionating agasoline-containing oil and separating therefrom a light fractioncontaining gasoline hydrocarbons and a heavier fraction composed ofhydrocarbons boiling above the gasoline range, simultaneouslyfractionating cracked vapors in a fractionating zone to form primaryreflux condensate and a lighter secondary reflux condensate, combiningthe primary reflux condensate. with said heavier fraction and heatingthe resultant mixture to cracking temperature under pressure whileflowing in a restricted stream through a heating zone, introducing theheated mixture into an enlarged reaction zone maintained under crackingconditions of temperature and pressure and effecting further conversiontherein, removing vaporous and liquid reaction products in commingledstate from the reaction zone and discharging the same into a separatingzone maintained under lower pressure than the reaction zone, combiningthe secondary reflux condensate with said light fraction and heating theresultant mixture, in an independent heating zone maintained at highertemperature than the first-named heating zone, to a. temperatureadequate to improve the antiknock value of the gasoline hydrocarbonscontained in the light fraction, discharging heated products directlyfrom said independent zone into the reduced pressure separating zone andseparating the oils therein into vapors and residue, supplying theseparated vapors to the fractionating zone as said cracked vapors, andfinally condensing the fractionated vapors.

2. A conversion process which comprises topping and fractionating crudepetroleum in a topping zone and separating therefrom a light fractioncontaining gasoline hydrocarbons and a heavier fraction composed ofhydrocarbons boiling above the gasoline range, simultaneouslyfractionating cracked vapors in a fractionating zone apart from saidtopping zone to form primary reflux condensate and a lighter secondaryreflux condensate, combining the primary reflux condensate with saidheavier fraction and cracking the resultant mixture under pressure in aconversion zone, discharging the cracked mixture into a separating zonemaintained under lower pressure than the conversion zone, combining thesecondary reflux condensate with said light fraction and heating theresultant mixture, in an independent heating zone maintained at highertemperature than said conversion zone, to a temperature adequate toimprove the anti-knock value of the gasoline hydrocarbons contained inthe light fraction, discharging heated products directly from saidindependent zone into the reduced pressure separating zone andseparating the oils therein into vapors and residue, supplying theseparated vapors to the fractionating zone as said cracked vapors, andfinally condensing the fractionated vapors.

CHARLES H. ANGELL.

